This invention relates to a fuel cell set for the generation of electric energy through the reaction of gaseous reactants and a liquid electrolyte which is circulated through the fuel cell set, as well as a method for operating this fuel cell set.
Fuel cells and fuel cell batteries generate electric energy in the form of direct current from chemical energy, for instance using hydrogen and oxygen. The efficiency is about 50 to 60%. With fuel cells connected in series, the available current depends on the size of the active area of the individual cells and the permissible area loading; the voltage depends on the number of cells. Heat is generated during the electrochemical reaction in which the chemical energy is converted into electric energy. This heat must be removed by means of a collant, such as water. As a rule, as much heat must be removed in a fuel cell battery by the coolant as the amount of useful energy that is taken from the battery. In addition to the reaction heat, reaction water is also produced in the electrochemical conversion, about 0.5 liter of water being produced per kilowatt-hour.
Since fuel cell batteries always consist of a fairly large number of cells which are electrically connected in series or in parallel because of the relatively low voltage of the individual cells, large units result when fuel cell batteries of large power rating are constructed. In addition and in contrast to classical batteries and storage cells, fuel cell batteries, moreover, require a number of auxiliary devices for continuous operation. On the other hand, such fuel cell batteries must meet certain requirements for specific application. For instance, if the field of locomotion or traction, such as in applications for mobile systems, they must be capable of functioning without inordinate sensitivity in inclined positions.